The invention disclosed herein relates to mowers of the type adapted for cutting grass and other vegetation on sloped surfaces, with the mower having a rearwardly positioned power unit and a forwardly positioned cutter unit with rear driving wheels powered by fluid driven motors driven by reversible variable speed pumps. More particularly, the invention relates to the mounting arrangement of the pumps which drive the wheel motors, with the pumps being mounted on the power unit in front of the driving engine of the power unit, with the pumps projecting forwardly from the power unit over the cutter unit so that the weight of the pumps is positioned forwardly of the power unit and tends to locate the center of gravity of the mower further forward and reduces the likelihood of tipping the mower over when operating on a steeply sloped surface.